driving a 10A solenoid

Hi all,

I am currently doing a project, which pulses a solenoid once every 2 - 3 seconds at the duration of 10000 - 20000 microseconds. It is controlled via arduino and powered by an external power supply through a TIP 122 transistor. The solenoid is activated when something passes through a laser interrupt.

However, because of the short ON duration of 10000 - 20000 microseconds, the solenoid is not able to reach its full force potential. It is not able to draw 10A within the ON duration. It draws roughly 1 amp only.

It would be good to know if over powering this solenoid for a short period of time would be possible or will it destroy the solenoid. If possible, what would be the suggested maximum voltage and current. If not, how else can I power the solenoid with an ON duration of 10000 - 20000 microseconds, while still allowing it to have its maximum push force.

Any other suggestions would be appreciated!

thank you!

////

The specs of the solenoid: 24volt DC 10A 10mm stroke 16kg force push type solenoid.

Power supply: 36 volt and 6 amp max

My code if needed:

int solenoidPin = 12 ; 

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(13, OUTPUT);
  pinMode(solenoidPin, OUTPUT);
  
  // the interrupt
attachInterrupt(digitalPinToInterrupt(2), lift, FALLING);
}

void loop()
{
  digitalWrite(13, HIGH);
  delay(1000);
  digitalWrite(13, LOW);
  delay(1000);
}

void lift(){

  delayMicroseconds(10); // delay before activating solenoid
  
  digitalWrite(solenoidPin, HIGH); // solenoid switched to ON
  delayMicroseconds(9950); // solenoid stays on for this amount of time

  digitalWrite(solenoidPin, LOW);  // solenoid switched to OFF
  
}

The activation of the solenoid depends on getting enough current through the winding for enough time to get it to move the plunger. If voltage applied for 1 second, there is plenty of time to build up the magnetic flux and operate. As the time reduces, the current does not get to the level required to build enough magnetic flux.

The coil inductance slows down the flux build up. Using a higher voltage for shorter pulses will increase the current quicker. As the pulses are short, the overall average current should not over heat the coil.

Weedpharma

I agree with weedpharma. The solenoid can handle 10A continuously. Perhaps you could even increase the voltage to 100V or 200V to get that 10A during the 10..20ms. The real problem is that you have the wrong solenoid. Is it something like this : www.ebay.com/itm/391181763636 You need a high speed solenoid.

Hi, What is the application that requires the operation of a solenoid of that size for such a short time?

Tom... :)

thanks for the clear explanation! I will give it a try and see how it goes.

weedpharma: The activation of the solenoid depends on getting enough current through the winding for enough time to get it to move the plunger. If voltage applied for 1 second, there is plenty of time to build up the magnetic flux and operate. As the time reduces, the current does not get to the level required to build enough magnetic flux.

The coil inductance slows down the flux build up. Using a higher voltage for shorter pulses will increase the current quicker. As the pulses are short, the overall average current should not over heat the coil.

Weedpharma

That is the solenoid I am using. Can you please explain or guide me as to a high speed solenoid? I have tried googling but a lot of them were referring to solenoid values.

thank you

Koepel: I agree with weedpharma. The solenoid can handle 10A continuously. Perhaps you could even increase the voltage to 100V or 200V to get that 10A during the 10..20ms. The real problem is that you have the wrong solenoid. Is it something like this : www.ebay.com/itm/391181763636 You need a high speed solenoid.

I am using the solenoid to bounce a ping pong ball continuously. When ping pong ball passes through a laser interrupt, the solenoid will then be triggered after a couple of microseconds. Please see attached photo, I do not know how to upload a video. It bounces, within 1 to 2 feet, but I want it to go higher.

TomGeorge: Hi, What is the application that requires the operation of a solenoid of that size for such a short time?

Tom... :)

|375x500

You need a much smaller solenoid with much lower mass. Make the mass of the plunger comparable with the mass of the ball and you'll get much better momentum transfer.

MarkT: You need a much smaller solenoid with much lower mass. Make the mass of the plunger comparable with the mass of the ball and you'll get much better momentum transfer.

Yes I have noticed that too. I fabricated a bigger piece to couple onto the plunger thinking it would cover more surface area but it made it harder to push the ping pong ball. The header piece is now removed.

I will try with a small solenoid and report back with results.

thanks

//EDIT

The solenoid did not work as well as hoped. The ping pong ball does not have enough force to go pass the problem of air resistance.

rotcivisme: Hi all,

I am currently doing a project, which pulses a solenoid once every 2 - 3 seconds at the duration of 10000 - 20000 microseconds. It is controlled via arduino and powered by an external power supply through a TIP 122 transistor. The solenoid is activated when something passes through a laser interrupt.

However, because of the short ON duration of 10000 - 20000 microseconds, the solenoid is not able to reach its full force potential. It is not able to draw 10A within the ON duration. It draws roughly 1 amp only.

It would be good to know if over powering this solenoid for a short period of time would be possible or will it destroy the solenoid. If possible, what would be the suggested maximum voltage and current. If not, how else can I power the solenoid with an ON duration of 10000 - 20000 microseconds, while still allowing it to have its maximum push force.

Any other suggestions would be appreciated!

thank you!

////

The specs of the solenoid: 24volt DC 10A 10mm stroke 16kg force push type solenoid.

Power supply: 36 volt and 6 amp max

My code if needed:

int solenoidPin = 12 ; 

void setup() {   // put your setup code here, to run once:   Serial.begin(9600);   pinMode(13, OUTPUT);   pinMode(solenoidPin, OUTPUT);     // the interrupt attachInterrupt(digitalPinToInterrupt(2), lift, FALLING); }

void loop() {   digitalWrite(13, HIGH);   delay(1000);   digitalWrite(13, LOW);   delay(1000); }

void lift(){

  delayMicroseconds(10); // delay before activating solenoid     digitalWrite(solenoidPin, HIGH); // solenoid switched to ON   delayMicroseconds(9950); // solenoid stays on for this amount of time

  digitalWrite(solenoidPin, LOW);  // solenoid switched to OFF   }

Issue #1 - Time Constant A coil with initially allow 0 Amps to flow. Then the amperage will increase, over time, per the Inductance and Resistance of your circuit. There is a Time Constant ( t = L / R ) that explains the increase in amperage curve, over time. Your Time Constant "t" appears to be much longer than your 10 - 20 millisecond Pulse. The proof is, the amperage in the solenoid coil is only 1 Amp after 10 - 20 milliseconds.

Issue #2 - Power Supply Amperage The solenoid can draw 10 Amps but the Power Supply is only rated at 6 Amps? Maybe, you need a Power Supply rated at 10 Amps or more?

Issue #3 - Plunger Weight Is the weight of the solenoid plunger excessively heavy to accelerate and fully extend within your required 10 - 20 milliseconds?

Issue #4 - Output Driver The TIP 122 Transistor may be a poor choice. The voltage drop across the TIP 122 can be, up to, 4 volts. 4 Volts x 10 amps = 40 Watts of wasted energy as heat A Mosfet may waste less energy as heat.

You could write a short sketch:

set x = 10 Loop () { Energize the output for x milliseconds Write value "x" to serial port Delay for 1/2 second Increase x by 1 }

You will quickly learn how long of pulse you really need to fully extend the plunger. That will give you an idea of much or how little you need to adjust your project.

I have a question. What would be better for the best bounce ? A metal surface on top of the plunjer or something soft or something elastic ? Or does that depend on the material of the ball ?

Koepel: I have a question. What would be better for the best bounce ? A metal surface on top of the plunjer or something soft or something elastic ? Or does that depend on the material of the ball ?

Doesn't really matter, just don't make it a sharp point or it'll skewer the poor ping pong ball! Momentum transfer depends on force and time, not the nature of the surfaces (its not friction).

The ultimate speed of the ball is limited by how fast the plunger moves too, so a light plunger and lots of current for a short time are crucial. At best you can get the ball about twice the speed of the plunger - all the bounce is in the ball itself, and that's about as bouncy as you can make something already.

Think about flicking a ping pong ball with your finger - it goes fast because your finger moves fast, and it doesn't really matter if you wear woolly gloves or not!

mrsummitville: Issue #1 - Time Constant A coil with initially allow 0 Amps to flow. Then the amperage will increase, over time, per the Inductance and Resistance of your circuit. There is a Time Constant ( t = L / R ) that explains the increase in amperage curve, over time. Your Time Constant "t" appears to be much longer than your 10 - 20 millisecond Pulse. The proof is, the amperage in the solenoid coil is only 1 Amp after 10 - 20 milliseconds.

Issue #2 - Power Supply Amperage The solenoid can draw 10 Amps but the Power Supply is only rated at 6 Amps? Maybe, you need a Power Supply rated at 10 Amps or more?

Issue #3 - Plunger Weight Is the weight of the solenoid plunger excessively heavy to accelerate and fully extend within your required 10 - 20 milliseconds?

Issue #4 - Output Driver The TIP 122 Transistor may be a poor choice. The voltage drop across the TIP 122 can be, up to, 4 volts. 4 Volts x 10 amps = 40 Watts of wasted energy as heat A Mosfet may waste less energy as heat.

I do understand that there is a time constant in relation to the induction and resistance. The longer of ON duration = higher current draw = more force. However I do want it to only pulse for a very short time and that is because a short pulse reacts better with the ping pong ball. By that I mean pulling the solenoid in about 3/4 of the way in and then stopping the current. Having the solenoid pulled at full will result in loud sound and big vibration. This is something I am trying to avoid. I do understand a longer pull will give it more speed and force.

I only have a desktop power supply with max rating 6amp at the moment, I am looking to get one with a higher rating.

The plunger has been redesigned and it weights less now.

I have looked at mosfets as well and have order some (Mosfet IRF520 N-Channel). They should be on there way.

Thank you for the detailed analysis!

MarkT: Doesn't really matter, just don't make it a sharp point or it'll skewer the poor ping pong ball! Momentum transfer depends on force and time, not the nature of the surfaces (its not friction).

The ultimate speed of the ball is limited by how fast the plunger moves too, so a light plunger and lots of current for a short time are crucial. At best you can get the ball about twice the speed of the plunger - all the bounce is in the ball itself, and that's about as bouncy as you can make something already.

Think about flicking a ping pong ball with your finger - it goes fast because your finger moves fast, and it doesn't really matter if you wear woolly gloves or not!

thank you for clarifying

A couple of other points a) your breadboard is not rated for 10 amps - you need good electrical connection when playing with high currents b) the ball acts as a piston in a cylinder, so you need to permit lots of air to get into the area of the solenoid so that the upward travelling ball isn't pulling a partial vacuum.

jackrae: A couple of other points a) your breadboard is not rated for 10 amps - you need good electrical connection when playing with high currents b) the ball acts as a piston in a cylinder, so you need to permit lots of air to get into the area of the solenoid so that the upward travelling ball isn't pulling a partial vacuum.

I did not know that there is a rating for breadboards...! that is good to know.

I am well aware of the potential vacuum problem. That was the first problem I run into, which it is kind of solved right now after playing with different channel sizes

Thinking more about the machine it might be useful to add a level action so the solenoid doesn't have to move so far - trade force for speed.

MarkT: Thinking more about the machine it might be useful to add a level action so the solenoid doesn't have to move so far - trade force for speed.

Did you mean lever?

If so, yes that was in my prototype. However, this is for an art project and I have a specific aesthetic for it... (You can say it is an artist's stubbornness haha)

Moving a solenoid for 3/4 is not easy. Once the plunger has some speed it is hard to stop. So if you want a big push from the plunger and still want it to stop at 3/4, that is in conflict with each other, you can't have both. Sorry, but that is just not possible. Even if you reverse the current to slow the plunger down, that would still not work.

There are free moving plungers, for example in some ding-dong doorbells. The plunger is still stopped at the 'ding' metal on one side and the 'dong' metal on the other side though. However, there must be free moving plungers with a spring... but I can't find them.

You are using a cheap solenoid from Ebay, and try to make it do things that is in contradiction with its natural behaviour. I'm thinking of a better way, but I don't know. I have many different air valves, but I have only a few solenoids. Maybe you can push the ball with a puff of air ? Most solenoids on Ebay have a 10mm stroke, maybe a solenoid with 20mm stroke is better ? Some solenoids have a rubber cushion inside to make them silent. What about a linear actuator ? As jackrae wrote: The ball is in a square box, with little ways for the air to move around the ball. With every push, the air has to squeeze itself around the ball downwards. What if you make the box bigger ? or put (big) holes in it for the air. Or use a frame with metal wires instead of a box. As MarkT wrote: What if you put the solenoid outside the box and use a lever for the ball ? Stop the lever with rubber/silicone cushions to avoid that the solenoid can make a full stroke. If you have a metal magnet rod, or just an iron rod, you can wind your own coil around a tube. Use rubber/silicone at the bottom, and a spring to avoid the plunger from jumping out the top too far.

When you look for another solenoid, don't assume that 20A is better than 10A. Maybe a solenoid of 1A is better in this situation.

I think you can win a lot when the air can easily move (away from the front of the ball and into the backside of the ball in both directions). For the solenoid, you could try to open a few ding-dong doorbells and see if you can use the solenoid part of it. Something like this : http://www.engineersgarage.com/insight/how-doorbell-works?page=4

Maybe stop the ball above the solenoid so that the plunger has time to accelerate before striking the ball.

Weedpharma

Or get yourself a supply of pressurised air and use a solenoid valve to supply a blast of air under the ball

A bagatelle relies entirely on the impact of the spring plunger to transfer potential energy (pull against the spring) into kinetic energy (impact against the ball) If you wish to retain a mechanical technique you might want to consider using the solenoid to trip a trigger mechanism rather imparting direct energy into the ball. The trigger could be "charged" by a separate motor driven spring tensioner.

////This is a video of how the piece was a week ago: https://www.youtube.com/watch?v=rDiexDDBzoY

////This is a video of how it was yesterday: https://www.youtube.com/watch?v=LopXKeSTazk

////This is something I did two years ago with just mechanics: https://vimeo.com/82623047

Koepel - thank you again for your suggestions. I did not mean stopping at 3/4 of the way. I just did not like the loud metal to metal collision, hence having the current stop when it is at 3/4 of the way, the sound decreases. I do understand the trading factor where I would not get as much acceleration compared to a full pull.

I got the cheap ebay one because it had a higher push force, so I naturally thought it would be better. Based on my experiments, a solenoid with a higher push force provided a higher height, hence I went for the ebay one.

Air values was one suggestion from my instructor, however pneumatics are awfully loud, and loud in a consistent way. Whereas a solenoid is only loud for a second. The air value would also make the ping ball "float" as oppose to having it "bounce". Sorry if I am giving a terrible explanation.

Making the box bigger was the first thing I tried, but because of the ball spinning, it creates the magnus effect. This causes the ball to move left / right, hitting the box, similar to a vibrating object. The fact that it hits the box more causes it to lose energy and hence does not travel as high.

The lever system is the ultimate back up plan. I am trying to avoiding connotations to a pinball machine.

I will try with more solenoids and see if I can get hold of some pinball solenoids. I heard they are very powerful. Also the suggestion to a longer stroke solenoid is actually something I have not thought of and it is a very smart one.

Thank you again

////

Weedpharma - I have tried that, thinking there would be less of a downward force canceling the upwards force provided by the solenoid. However, the effects are roughly the same.

////

jackrae - mechanical advantage was the first thing I went for, but I was not able to design something that would match the aesthetic of my piece.

I apologize if I seem to be being difficult here with the options suggested..

rotcivisme: I do understand that there is a time constant in relation to the induction and resistance. The longer of ON duration = higher current draw = more force. However I do want it to only pulse for a very short time and that is because a short pulse reacts better with the ping pong ball. By that I mean pulling the solenoid in about 3/4 of the way in and then stopping the current. Having the solenoid pulled at full will result in loud sound and big vibration. This is something I am trying to avoid. I do understand a longer pull will give it more speed and force.

I only have a desktop power supply with max rating 6amp at the moment, I am looking to get one with a higher rating.

The plunger has been redesigned and it weights less now.

I have looked at mosfets as well and have order some (Mosfet IRF520 N-Channel). They should be on there way.

Thank you for the detailed analysis!

thank you for clarifying

Sorry, I did not mean to imply that you [u]should[/u] increase your pulse width. Just that you [u]could[/u] increase your pulse width with a TEST Sketch for diagnostic purposes, to determine how far off your current design is from Full Plunger Extension.

You previously stated that you are only pushing 1 amp through the 10 Amp Solenoid. And since your ON-TIME is a small percentage, you need more voltage.

If you do not have access to a 72 Volt P/S then make a Voltage Doubler using 2 mosfets, 2 diodes and 2 caps.